Shipping container for radioactive material

ABSTRACT

A body means includes inner and outer shell means having radiation shielding means therebetween and including a radioactive material receiving central cavity which is filled with liquid coolant during shipment. Expansion means in the form of an annular tank is disposed in a void defined between the shielding means and the outer shell means, this tank receiving liquid coolant from the cavity when the coolant expands upon an increase in temperature thereof and returning coolant to the central cavity when the coolant contracts upon a decrease in temperature.

ilnitetll Stat ?eterson [54] SElllllPlPlNG CONTAENER lFOlR 1 May 1, 1973 Primary Examiner-James W. Lawrence Assistant Examiner- Davis L. Willis Attorney-Robert L. Lehman; Fred Floersheimer and Jay D. Gordon 57 ABSTRACT A body means includes inner and outer shell means having radiation shielding means therebetween and including a radioactive material receiving central cavity which is filled with liquid coolant during shipment. Expansion means in the form of an annular tank is disposed in a void defined between the shielding means and the outer shell means, this tank receiving liquid coolant from the cavity when the coolant expands upon an increase in temperature thereof and returning coolant to the central cavity when the coolant contracts upon a decrease in temperature.

5 Claims, 4 Drawing Figures Patented ay 1, 1973 2 Sheets-Sheet 1/ ////1 H I8 1l IN VENTOR REUBEN W. PETERSON A! a. 6on9 ATTORNEY Patented May 1, 1973 2 Sheets-Sheet 2 If/Iii? REUBEN W. PETER SON D M MW SHIPPING CONTAINER FOR RADIOACTIVE MATERIAL BACKGROUND OF THE INVENTION present invention may be utilized for shipping any sort of radioactive material and is particularly useful for shipping irradiated nuclear fuel elements and the like for transportfrom one place to another on railroad cars or trailers.

Shipping containers of the present day design are self-pressurized, or in other words, after the containers are loaded they are closed pressure-tight and the temperature and pressure of the internal liquid coolant increases to the point where the heat transfer from the shipping container is equal to the heat being released from the fuel elements being shipped within the container. When this occurs, a so-called equilibrium condition has been reached.

Shipping containers employing a liquid coolant such as water have been employed for sometime, and such containers have generally been of the type wherein the containers are shipped in a vertical upright condition so that the closure head for the shipping container is disposed at the top of the container and the fuel elements within the container are shipped in a vertical position.

The present invention is particularly directed to shipping containers which are shipped in a horizontal position, or in other words, the longitudinal axis thereof extends horizontally and the fuel elements disposed therewithin are supported in a horizontal position. The problems encountered with this construction are somewhat different from those wherein the shipping container is disposed in a vertical position. When the shipping container is disposed in a vertical orientation, it is not necessary to fill the cavity with liquid coolant such as water because the fuel elements therewithin do not extend to the top of the cavity within the container. There is accordingly a void between the upper level of the liquid coolant in the container and the top of the container, this void accommodating thermal expansion of the liquid coolant.

However, when a shipping container of the type which is shipped in a horizontal position is employed, the cavity within the container must be completely filled with liquid coolant at all times since some of the fuel elements are disposed at the top of the cavity within the container. It accordingly becomes necessary to provide expansion means somewhere in the container for receiving a certain amount of liquid coolant upon thermal expansion thereof. This thermal expansion occurs after the time when the shipping container is closed and sealed until the equilibrium condition aforedescribed is reached and also during transport when variable ambient temperatures are encountered. In a typical shipping container, the expansion which occurs exceeds one cubic foot, and it is difficult to provide that much volume within the central cavity of a conventional shipping container without uncovering the fuel elements therein. This volume cannot be provided within the cavity of the container itself since it is necessary that the fuel rods be completely covered with coolant when the shipping container is in the horizontal shipping position.

It has been proposed to provide an external expansion or overflow tank to receive the expanding coolant, but such external tanks or fittings are vulnerable to damage in an accident and increase the probability of the loss of coolant SUMMARY OF THE INVENTION In the present invention, expansion means in the form of a tank is provided in the annular void disposed between the radiation shielding means and the outer shell means of the container. This expansion tank is in communication with the radioactive material receiving cavity within the body means of the shipping container. The expansion means is disposed within the basic body structure of the shipping container and in no way compromises the integrity of the container.

Conduit means is provided having one end thereof in communication with the top part of the cavity within the container, the opposite end of the conduit means being in communication with the lower part of the expansion tank. When the liquid coolant such as water expands upon increase in temperature thereof, the liquid coolant passes through the conduit means into the lower part of the expansion tank to form a pool that rises within the expansion tank and compresses the gas within the tank. When the liquid coolant subsequently cools, the liquid coolant flows back into the cavity within the container thus keeping the container cavity completely full and ensuring that the fuel elements are covered with liquid coolant at all times.

Suitable vent means and drain means is provided in communication with the expansion tank to initially establish proper levels and enable the tank to be drained and flushed when desired. The expansion tank can also be initially pressurized with air if so desired.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal broken away section illustrating a shipping container according to the present invention;

FIG. 2 is an enlarged view of a portion of the structure as shown in FIG. 1;

FIG. 3 is a sectional view taken substantially along line 33 of FIG. 1 looking in the direction of the arrows; and

FIG. 4 is a longitudinal section illustrating a modified form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings wherein like reference characters designate corresponding parts throughout the several views, a first form of the invention is illustrated in FIGS. 1-3, inclusive, wherein the body means of a horizontally disposed shipping container includes an inner shell means 10 having a bottom 12 and an outer shell means 14 having a bottom l6,'the inner and outer shell means being formed of a suitable material such as stainless steel and the like. A plurality of cooling fins 15 are provided on the outer surface of the outer shell means.

Radiation shielding means 18 is provided between the inner and outer shell means. A void 20 is provided between one end of the radiation shielding means 18 and the outer shell means adjacent one end of the shipping container.

The opposite open end of the shipping container is closed off by a closure head 26 incorporating suitable radiation shielding material, this closure head being held in operative position by a plurality of cap screws 28 threaded through suitable holes provided in the closure head and the adjacent portion of the body means.

A central radioactive material receiving cavity 30 is defined within the body means, this cavity being filled with a body of liquid coolant 32 such as water during shipping so as to provide the necessary cooling for fuel elements supported within the cavity.

A passage 34 formed in the body means is in communication with the top of cavity 30, one end of passage 34 being threaded and receiving a plug 36 which is adapted to be removed to serve as a container and expansion tank vent when it is desired to drain or flush the expansion tank hereinafter described. Passage 34 is in communication with a conduit 38 which in turn joins with a conduit 40 supported within an annular expansion tank 42 formed of a suitable material such as stainless steel or the like and being of suitable cross-sec tional configuration. This expansion tank is disposed within the aforedescribed void space 20, the expansion tank normally being filled with a gas such as air or the like. The opposite open end 44 of conduit 40 is disposed at the bottom of tank 42 so that liquid coolant passing through conduit 40 will enter the expansion tank at the lowermost portion thereof and the conduit end will always be submerged when coolant is forced into the expansion tank.

A passage 50 is provided in the body means and is in communication with the lower part of the expansion tank, the outer end of this passage being threaded to receive a plug 52 which can be selectively removed when it is desired to drain the expansion tank.

Referring now to FIG. 4 of the drawings, a modified form of the invention is illustrated wherein similar parts to those previously described have been given the same reference numerals primed. In this form of the invention, a groove 60 extends around the inner periphery of the body means. A conduit 62 is disposed within 180 of this groove and it is open at the top end 64 thereof so as to be in communication with the top part of cavity 30. The lower end of conduit 62 is in communication with a further conduit portion 66 the open end 68 of which is in communication with the lowermost part of expansion tank 42'.

A passage 70 is in communication with the top part of groove 60 and the outer end thereof is threaded to receive a plug 72 which can be selectively removed to vent the container and expansion tank. A further passage 74 formed in the body means is in communication with conduit portion 66, the outer end of passage 74 being threaded and receiving a plug 76 which can be selectively removed when it is desired to drain the expansion tank.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

What is claimed is:

l. A shipping container for radioactive material said container adapted to be used in a horizontal position and comprising a body including an inner shell defining a radioactive material receiving cavity adapted to be completely filled with water, an outer shell spaced from said inner shell and having a plurality of cooling fins extending outwardly radially from the outer surface thereof, radiation shielding means disposed in the space between said inner shell and said outer shell, and expansion means in said body comprising a fluid-tight chamber of annular configuration disposed between the inner and outer shells of said body and in a plain substantially at right angles to the longitudinal axis thereof, and fluid conduit means in said body, one end of'said fluid conduit means being arranged at the upper surface of the water in said radioactive material receiving cavity, the opposite end of said fluid conduit means being connected into the bottom of said annular fluidtight chamber.

2, A shipping container for radioactive material according to claim 1 wherein a void of annular configuration is provided between said radiation shielding means and said outer shell, and said fluid-tight chamber is disposed within said void.

3. A shipping container for radioactive material according to claim 1 wherein vent means is provided in the upper wall of said body in communication with said fluid-tight chamber,

4. A shipping container for radioactive material according to claim 1 wherein drain means is provided in the bottom wall of said body in communication with said fluid-tight chamber.

5. A shipping container for radioactive material according to claim 1 wherein an annual grove is formed in the inner surface of said body and said fluid conduit means is engaged in said annular grove. 

1. A shipping container for radioactive material said container adapted to be used in a horizontal position and comprising a body including an inner shell defining a radioactive material receiving cavity adapted to be completely filled with water, an outer shell spaced from said inner shell and having a plurality of cooling fins extending outwardly radially from the outer surface thereof, radiation shielding means disposed in the space between said inner shell and said outer shell, and expansion means in said body comprising a fluid-tight chamber of annular configuration disposed between the inner and outer shells of said body and in a plain substantially at right angles to the longitudinal axis thereof, and fluid conduit means in said body, one end of said fluid conduit means being arranged at the upper surface of the water in said radioactive material receiving cavity, the opposite end of said fluid conduit means being connected into the bottom of said annular fluid-tight chamber.
 2. A shipping container for radioactive material according to claim 1 wherein a void of annular configuration is provided between said radiation shielding means and said outer shell, and said fluid-tight chamber is disposed within said void.
 3. A shipping container for radioactive material according to claim 1 wherein vent means is provided in the upper wall of said body in communication with said fluid-tight chamber.
 4. A shipping container for radioactive material according to claim 1 wherein drain means is provided in the bottom wall of said body in communication with said fluid-tight chamber.
 5. A shipping container for radioactive material according to claim 1 wherein an annual grove is formed in the inner surface of said body and said fluid conduit means is engaged in said annular grove. 